I had a friend back in the day who was a 727 pilot for Eastern, and we have had a bunch of conversations about this subject; this is the Reader's Digest form of the complicated arrangement.
- Eastern ordered 4 747s which would be delivered to TWA, configured in the TWA layout, and maintained by TWA, but operated by Eastern. However, there was a clause that the aircraft could be refused by Eastern, at which point the airplane would go into TWA service.
-After some further thinking, Eastern refused the 747s, and TWA took delivery. These were leased out to Pan Am.
- Shortly thereafter, National (one of Eastern's biggest competitors on the NE-Florida sector) announced they would acquire two 747s. To keep up with the competition, Eastern made an "in-your-face" move and inked a lease for two year-round and a third for the busy winter travel season from Pan Am.
-The two 747s arrived in time for the winter with the third on its way a few months later. Almost immediately, they ran into trouble with the frequent cycles for which the 747 was not designed for
(and especially not the -100). After a few months, they were all returned and Eastern decided to sit tight and wait for their L-1011s to be delivered.